Can i block a specific game?

Hi there,

Content restrictions can be set for child accounts, and exceptions can be made for specific games. You'll need the parental account to set to set it.

More info can be found
here.

You can't set it for specific games as far as I know but you can block teen or M gamescontent

Thanks. It doesn't specifically say the block feature prevents future game encounters just communications. And i feel like I've seen a few previously blocked players again. Can you please confirm this.

If you don’t want to receive communications from a specific player on Xbox One, you can block that player. Do this by selecting the player’s gamertag from within the game and blocking the player. If the person is no longer playing the game, you can search
and block the person through the Profile app.

The block only applies to communications such as messaging. The blocked player will not be able to send you messages, unless you first send a message to that player. However, a blocked player can still join games with you.

Source: Block a gamertag

Game sharing outside your physical household is a violation of terms of service and can lead to account and console bans.

Activision specifically blocks sharing for this reason.